1. Field of the Invention
The present invention relates to a CVD (chemical Vapor Deposition) apparatus and a CVD method, and more particularly, a CVD apparatus and a CVD method for forming an Al/Cu multilayered film.
2. Description of the Background
In a semiconductor device, wiring (e.g., metal) is generally formed on a device formation region on a silicon semiconductor wafer by, for example, etching an Al--Cu film formed by sputtering using an Al--0.5 wt % Cutarget.
Recently, with the trend toward high integration of the semiconductor device, it has been desired to reduce the wiring width. However, it is difficult for a hitherto-used sputtering method to form a fine wiring which will be required by a design rule in future.
Then, as a technique replaceable for the sputtering method, a CVD method has been studied. Since the CVD method includes a vapor deposition step, a film is easily formed on a complicated substrate surface and minute portions such as portions having a large aspect ratio and contact holes.
However, it is difficult to form the Al--Cu film suitable for wiring by the CVD method.
To form the Al--Cu film, conventionally employed is a method in which a Cu component is added to an Al film (CVD) formed by the CVD method. In the conventional method, the Cu component is diffused into the Al film (CVD) by depositing an Al--Cu film or a Cu film on the Al film (CVD) by sputtering and annealing the obtained film.
The Al--Cu film of this type is reported in "Symposium on VLSI technology Digest of Technical Papers (1996), p42".
In the case where the Cu component is dispersed into the Al film (CVD) by use of a single wafer process system having a multichamber type, two process chambers are required; one is to form the Al film by the CVD method and the other is to form the Al--Cu film or the Cu film by sputtering. However, film-formation has to be performed two times by transporting a single wafer between two process chambers. As a result, the throughput thereof inevitably decreases.
To overcome the decrease in throughput, if a plurality of chambers are prepared for each of the Al-film formation and Al--Cu film or the Cu film formation, the entire apparatus becomes quite large, raising a manufacturing cost.